Flat panel display devices have been booming with the evolution of optoelectronic and semiconductor technologies, and in many types of flat panel display devices, liquid crystal display (LCD) devices and organic light-emitting diode (OLED) display devices have become the mainstream of market due to their many superior characteristics such as high space utilization efficiency, low power consumption, radiation-free and low electromagnetic interference.
Currently, amorphous silicon thin film transistor (a-Si TFT) is widely applied to switch element of the LCD display and OLED display. But the a-Si TFT have limits of meeting the requirements such as thin, light weight, high-finesse, high brightness, high reliability and low power consumption. Compared with the a-Si TFT, the LTPS TFT has significant advantages on the aspects of satisfying the above requirements.
However, it needs two mask processes to poly-Si layer for forming heavily doped region and lightly doped region, and then injecting ions twice for forming heavily doped layer and lightly doped layer in currently low temperature poly-Si TFT. Therefore, the manufacture method is complications and high cost.